Biology: Cell Structure and Genetics

Cell Theory: All living organisms are composed of cells; the cell is the basic unit of life; all cells arise from pre-existing cells.
Prokaryotic vs. Eukaryotic Cells:
- Prokaryotic: No nucleus, smaller, simpler (e.g., bacteria).
- Eukaryotic: Nucleus present, larger, more complex (e.g., plant and animal cells).
Organelles:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Powerhouse of the cell, site of ATP production.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum: Rough (with ribosomes) for protein synthesis; Smooth for lipid synthesis.
- Golgi Apparatus: Modifies, sorts, and packages proteins.
- Lysosomes: Digestion and waste removal.

DNA Structure: Double helix, nucleotides (adenine, thymine, cytosine, guanine).
Gene: Segment of DNA that codes for a protein.
Mendelian Genetics:
- Law of Segregation: Alleles segregate during gamete formation.
- Law of Independent Assortment: Genes for different traits segregate independently.
Punnett Squares: Tool for predicting genotypic and phenotypic ratios.

Theory of Natural Selection: Survival of the fittest; organisms with advantageous traits reproduce more successfully.
Speciation: Process by which new species arise.
Fossil Record: Provides evidence of change over time.
Common Ancestry: All life shares a common ancestor.

Ecosystems: Interactions between living organisms and their environment.
Biomes: Large geographical areas with distinct climates and ecosystems (e.g., deserts, forests).
Food Chain/Web: Shows energy flow; producers (plants) → consumers (herbivores, carnivores) → decomposers.
Population Dynamics: Study of how populations change over time and space.

Organ Systems:
- Circulatory: Transports blood, nutrients, gases.
- Respiratory: Facilitates gas exchange (oxygen and carbon dioxide).
- Digestive: Breaks down food, absorbs nutrients.
- Nervous: Controls body functions, processes information.
Homeostasis: Maintaining stable internal conditions despite external changes.

Photosynthesis: Process by which plants convert light energy into chemical energy (glucose).
Plant Structure:
- Roots: Absorb water and nutrients.
- Stems: Support and transport.
- Leaves: Main site of photosynthesis.
Reproduction: Asexual (via runners, tubers) and sexual (pollination, seeds).

Types of Microorganisms:
- Bacteria: Prokaryotic, diverse, some pathogenic.
- Viruses: Non-living, require a host to replicate.
- Fungi: Eukaryotic, decomposers, some pathogenic.
Role in Ecosystems: Nutrient cycling, decomposition, symbiosis.

Cell Theory: Fundamental principles defining that all living things are made of cells, which are the basic life units, and cells arise from existing cells.
Prokaryotic Cells: Characterized by no nucleus, smaller size, and simpler structure, typical examples include bacteria.
Eukaryotic Cells: Feature a defined nucleus, larger and more complex than prokaryotic cells, including plant and animal cells.
Nucleus: Houses genetic material (DNA) and controls cellular activities.
Mitochondria: Known as the powerhouse of the cell, where ATP (energy) production occurs.
Ribosomes: Sites of protein synthesis, found freely in the cytoplasm or attached to the endoplasmic reticulum.
Endoplasmic Reticulum (ER): Divided into rough ER (with ribosomes for protein synthesis) and smooth ER (involved in lipid synthesis).
Golgi Apparatus: Responsible for modifying, sorting, and packaging proteins for secretion or use within the cell.
Lysosomes: Contains digestive enzymes to break down waste materials and cellular debris.

DNA Structure: Composed of a double helix formed by nucleotides, including adenine (A), thymine (T), cytosine (C), and guanine (G).
Gene Definition: A specific segment of DNA that encodes for a particular protein.
Mendelian Genetics:
- Law of Segregation: Each allele segregates into separate gametes during their formation.
- Law of Independent Assortment: Inheritance of one trait is independent of another trait's inheritance.
Punnett Squares: A graphical tool used to predict the probability of genotypic and phenotypic outcomes of genetic crosses.

Natural Selection: The process where organisms with advantageous traits are more likely to survive and reproduce, often summarized as "survival of the fittest."
Speciation: The evolutionary process through which new species arise, often due to environmental factors and reproductive isolation.
Fossil Record: A historical archive that provides evidence of biological evolution and changes over time.
Common Ancestry: The concept that all life on Earth shares a common ancestor, emphasizing genetic links among diverse organisms.

Ecosystems: Defined by the interactions among organisms and their physical environment, encompassing living and non-living components.
Biomes: Large ecological areas on Earth with distinct climatic conditions and life forms, such as deserts and forests.
Food Chain/Web: Illustrates the flow of energy through an ecosystem, starring producers (plants) followed by consumers (herbivores, carnivores) and decomposers.
Population Dynamics: Examines how and why populations change in size, distribution, and composition over time.

Organ Systems:
- Circulatory System: Responsible for the movement of blood, nutrients, and gases throughout the body.
- Respiratory System: Enables gas exchange, primarily oxygen intake and carbon dioxide expulsion.
- Digestive System: Breaks down food to absorb essential nutrients into the bloodstream.
- Nervous System: Controls body functions and processes sensory information for responsiveness.
Homeostasis: The ability of an organism to maintain stable internal conditions regardless of external environmental changes.

Photosynthesis: The biochemical process through which plants convert solar energy into chemical energy stored in glucose.
Plant Structure:
- Roots: Facilitate water and nutrient absorption from the soil.
- Stems: Provide structural support and transport nutrients and water.
- Leaves: The primary site for photosynthesis, where gas exchange occurs.
Reproductive Strategies: Includes asexual reproduction (via runners or tubers) and sexual reproduction (pollination leading to seed production).

Types of Microorganisms:
- Bacteria: Diverse group of prokaryotic organisms, some of which can cause diseases.
- Viruses: Non-living infectious agents that require host cells for replication.
- Fungi: Eukaryotic decomposers, playing a key role in nutrient recycling; some are pathogenic.
Ecological Role: Microorganisms contribute to nutrient cycling, decomposing organic matter, and establishing symbiotic relationships with other organisms.

Genetic Engineering: The manipulation of organisms' DNA to express desired traits, commonly seen in genetically modified organisms (GMOs).
CRISPR: An advanced gene-editing technology that enables precise modifications of DNA sequences in living organisms.
Bioremediation: The process involving the use of microbes to clean up contaminated environments, such as oil spills or heavy metal pollution.